On Friday 1 September 1939 German forces had
invaded Poland which marked the
beginning of World War II, and in June 1941, Germany had
invaded the Soviet Union which created the
Eastern Front. In late September 1943, III.
Gruppe of JG 52 was equipped with the
Messerschmitt Bf 109 G and fought in the
Battle of the Caucasus and was based at
Zaporizhia. In October, III.
Gruppe flew combat missions over the right flank of the
1st Panzer Army and the left flank of
6th Army during the
Battle of the Dnieper.
Eastern Front Birkner claimed his first aerial victory on 1 October 1943 over a
P-39 Airacobra in combat south-southwest of
Bolschoj Tokmak. That day, III.
Gruppe had claimed 17 aerial victories in an encounter with
Ilyushin Il-2 ground-attack aircraft and their fighter escort. Birkner claimed his second aerial victory on 4 October over a
Lavochkin-Gorbunov-Gudkov LaGG-3. The following day he shot down a
Lend-Lease Douglas A-20 Havoc bomber also referred to as a "Boston". On 9 October, he claimed another LaGG-3 fighter shot down followed by two further claims over LaGG-3 fighters on 11 October. On 19 October, III.
Gruppe moved to an airfield at
Kirovograd, present-day Kropyvnytskyi where they stayed until 31 October. Here Birkner claimed a LaGG-3 fighter on 21 October, two LaGG-3 fighters on 24 October, a
Bell P-39 Airacobra fighter and another LaGG-3 fighter on 25 October, and an Il-2 ground-attack aircraft and another P-39 fighter on 29 October. On 1 November, III.
Gruppe was moved to
Apostolove fighting in the combat area between
Nikopol and
Zaporizhzhia. Adverse whether conditions rendered the airfield unusable and the
Gruppe temporarily used an airfield near Kirovograd from 12 to 20 November. By the end of 1943, Birkner had claimed 24 aerial victories in total. Over the next few months Birkner often flew as
Rottenflieger (
wing man) to the high scoring aces Günther Rall and
Erich Hartmann, claiming many of his victories whilst flying with them. On 3 January 1944, Birkner claimed two LaGG-3 fighters shot down, taking his total to 26 aerial victories. The
Gruppe moved to an airfield at
Mala Vyska on 7 January where they stayed for three days. On 10 January, the
Gruppe moved to an airfield at Novokrasne located approximately south-southwest of
Novoukrainka. While based at Novokrasne, elements of III.
Gruppe also operated from
Ivanhorod (11 to 13 January), at
Velyka Lepetykha (3 to 22 February), and
Mykolaiv (2 to 23 February). Five days later, Birkner claimed five P-39 fighters shot down near Kirovograd, one of which was not confirmed. In April, he claimed a further 29 victories, including six in one day on 19 April making him an "
ace-in-a-day" for the first time, taking his total to 60 aerial victories. Birkner received the
Honor Goblet of the Luftwaffe () on 24 April. In May, he claimed 17 victories, including another "ace-in-a-day" achievement on 30 May. III.
Gruppe relocated to
Roman on 1 June. On 3 June, Birkner claimed three
Lavochkin aircraft shot down north of
Iași. On 24 June, the
United States Army Air Forces' (USAAF)
Fifteenth Air Force attacked various targets in Romania with 377 bombers. A fraction of this attack force, consisting of 135
Consolidated B-24 Liberator and
Lockheed P-38 Lightning and
North American P-51 Mustang fighters, headed for the
Ploiești oilfields. Defending against this attack, Birkner claimed a P-51 shot down, his 91st aerial victory. Birkner was awarded the
Knight's Cross of the Iron Cross () on 27 July 1944 for 98 victories.
Squadron leader and death On 1 October 1944, Birkner was appointed
Staffelkapitän (squadron leader) of 9.
Staffel of JG 52. He thus succeeded
Oberleutnant Hartmann who was transferred. At the time of this assignment, III.
Gruppe was based in
Warzyn Pierwszy, Poland. The airfield was located approximately west of
Jędrzejów. The
Gruppe was under the command of
Hauptmann Wilhelm Batz and
Oberstleutnant Hermann Graf had just taken over the JG 52 as
Geschwaderkommodore (wing commander). On 8 October, III.
Gruppe moved to an airfield near Lobellen, present-day Tushino located approximately east-southeast of
Tilsit, present-day Sovetsk, on the south bank of the
Memel, present day Neman River. Here, Birkner claimed an Il-2 ground-attack aircraft shot down on 14 October, his 100th aerial victory. He was the 95th Luftwaffe pilot to achieve the century mark. Two days later on 16 October, he became an "ace-in-a-day" for the second time, claiming four LaGG fighters and a single Il-2 ground-attack aircraft. The
Gruppe moved to an airfield named Hasenfeld, also referred to as Jürgenfelde, located approximately south of
Insterburg, present-day Chernyakhovsk, on 20 October where they stayed until 7 November. Here Birkner claimed five further aerial victories over LaGG fighters, one on 23 October, and two each on 25 and 27 October respectively. On 7 November, III.
Gruppe again moved to the airfield at Warzyn Pierwszy. On 12 December, the
Gruppe relocated to
Krakau, present-day Kraków. Two days later, Birkner was killed in a flying accident when his Bf 109 G-14/U4 (
Werknummer 510531—factory number) suffered engine failure during the landing approach at Krakau. Following his death, command of 9.
Staffel was passed on to
Hauptmann Otto-Karl Klemenz. ==Summary of career==